Cognitive functioning among patients with schizophrenia in a Nigerian hospital: a comparison with mood disorder

OBJECTIVE: The study aimed to investigate correlates of cognition among patients with schizophrenia. METHODS: Over a three month period, in-patients diagnosed with schizophrenia (n = 50) and mood disorders (n = 50) were recruited into the study. Both groups of patients were assessed using the Schedules for Clinical Assessment in Neuropsychiatry (SCAN), the Annett Hand Preference Questionnaire (AHPQ) and the Global Assessment of Function Scale (GAF). Patients with schizophrenia were further assessed using the Positive and Negative Syndromes Scale, PANSS and the Clinical Global impression (CGI). The cognitive screen section of SCAN (comprising Verbal Trails Test and Mini Mental State examination, MMSE) and the cognitive factor of PANSS were used to assess cognitive function. RESULTS: No differences were found in the cognitive profile of patients with schizophrenia and mood disorder. Among patients with schizophrenia, poor verbal performance was associated with the negative or mixed syndrome (p = 0.004), left or mixed handedness (p = 0.013), greater illness severity (p = 0.030) and lower GAF scores (p = 0.039). Poor performance on MMSE correlated with higher total PANSS score (p = 0.022) and was also associated with the negative or mixed syndrome (p = 0.003) and lack of clinical improvement (p = 0.035). CONCLUSION: Patients with the negative or mixed schizophrenia syndrome may suffer more cognitive deficit. Poor verbal performance among patients with schizophrenia may be associated with left or mixed handedness, more severe illness and poor functioning.